(a) Field of the Invention
The present invention relates to a high-speed boring tool and the manufacturing process of the same; more particularly to a high-speed boring tool that dispenses with gyration balancing calibration in replacing boring bar body of a different bore size and that also includes a foolproof securing structure for fast replacement of boring bar body when fine-tuning bore sizes.
(b) Description of the Prior Art
FIG. 19 of a prior art in the accompanying drawings, shows a bore-size adjustable boring tool 10: an adjusting screw drives a screw lock 12, and an adapter 13 changes the position of the tip of a disposable insert 14 when adjusting the bore size. However, once the position of the adapter 13 changes, the gyration balancing of the bore tool must be readjusted, too, to avoid making a bore of an imperfect circle as a result of boring at high revolving speed. Re-adjustment of the gyration balancing is in general made by means of a gyration balancing weight structure including an adjusting screw 15 and a weight 16. The position of the weight 16 is adjusted and placed on a gyration-balancing machine for calibration. Both the readjusting process and the examination of bored circles produced by a boring tool are time-consuming, thus requiring higher production cost. Some manufacturers try to reduce the ‘off-target’ threshold of a bored circle by reducing revolving speed (at approximately 2000 r/pm or revolution/per minute), which entails undesired consequences such as slower processing speed, more surface roughness, and reduced surface gloss.
FIGS. 16, 17, and 18, respectively, show a perspective view and two sectional views of U.S. application Ser. No. 10/680,061. There is no restriction in operational direction either in the engagement between a securing threaded hole 23′ and a limiting block 231′, or in the engagement between a positioning threaded hole 24′ and an elastic positioning block 241′ for an adapter 20′; instead, misplacement of the limiting block 231′ for the elastic positioning block 241′ (or vice versa) is avoided by way of different sizes of the securing threaded hole 23′ and the positioning threaded hole 24′, which are designed to be of different diameters. Whereas an elastic lever is disposed on the tip of the elastic positioning block and the support for the elastic lever must be provided on the top for a boring bar body 30′ to tightly engage the adapter 20′; therefore, close engagement between a boring bar body 30′ and the adapter 20′ will not be possible when the elastic positioning block 241′ is mounted in a reverse way.
Two limitation points 271′ and 272′ (in FIGS. 16, 17 and 18) on the end surface of the adapter include two inserted limiting pins. In the present invention, a fillister structure is provided in lieu of both inserted limiting pins in prior arts for easy of production and hence for reduced production cost while achieving the same purpose.